GB2069126A

GB2069126A - Improvements in or relating to heat recovery apparatus

Info

Publication number: GB2069126A
Application number: GB8103465A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-02-06
Filing date: 1981-02-04
Publication date: 1981-08-19
Also published as: GB2069126B

Abstract

Apparatus in which clean water is heated by contaminated water, particularly water containing solids, comprises a chamber 11 into which tubes 30, Fig. 3, extend from an inlet (e.g. a header 12), the tubes opening at their outlet ends into the chamber. Other tubes 31 extend from a clean water inlet (e.g. a header 13) and through the tubes 30 to an outlet (shown as a chamber 14 which may be adjacent the header 13 or adjacent the header 12). In use contaminated water is passed along the tubes 30, whilst clean water is passed along the tubes 31. Means for flushing pipes 30 to a drain, should they become blocked by silt or other solids may comprise causing clean water to flow via a flushing line 25 through the chamber 11 and, with either a forward or reverse flow, through the tubes 30. Each tube 31 may be a twisted U-tube with a spirally-fluted wall or with external helical fins. <IMAGE>

Description

SPECIFICATION Improvements in or relating to heat recovery apparatus This invention relates to apparatus for recovering heat from contaminated water particularly water containing solids.

According to the present invention there is provided apparatus for recovering heat from contaminated water comprising, a chamber having a drain, an inlet for contaminated water, a plurality of pipes extending across the chamber, each of the pipes having one end connected to the inlet for contaminated water and being open to the chamber at their respective other end, and inlet for clean water, a plurality of further pipes, each of the further pipe extending from the clean water inlet along a respective one of the first.

mentioned pipes to an outlet and means for flushing the first mentioned pipes, the arrangement being such that, in use, contaminated water flows from the inlet along the first mentioned pipes into the chamber heating the clean water flowing along the further pipes.

A header may be provided at one or both of the inlets.

The chamber may be elongate and the first mentioned pipes may extend from one end of the chamber parallel to the axis of the chamber. In this latter case the further pipes may extend from the other end of the chamber.

The further pipes may be doubled back within the first mentioned pipes so that they enter and exit from the first mentioned pipes at the open other end thereof. The walls of the further pipes may be deformed to create one or more flutes, each flute comprising both an internal spiral groove and a complementary spiral rib.

Alternatively the further pipes may have ribs or fins extending lengthwise along their outer walls, in which case the ribs may be spirals.

The means for flushing may be arranged to flush the first mentioned pipes in either direction.

Specific embodiments of the invention will now be described with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic view of heat recovery apparatus; Figure 2 is a cross-section through a chamber of the apparatus at Figure 1 along the line A-A; and Figure 3 is an enlarged longitudinal crosssectional view of a pipe arrangement of the apparatus shown in Figures 1 and 2.

In many industrial processes, such as dyeing, and in service processes, such as laundering, hot water is required for the process and the process results in a reasonably continuous discharge of contaminated hot water. Because of its contamination this water cannot be reused in the process and frequently all the heat in that water is lost. This is also true of large kitchens or blocks of flats, where considerable quantities of hot water are used and then poured down the drain. Because of the contamination of the water traditional heat exchangers are often not suitable for use for such water because they become blocked by the contaminating material.

Referring to Figure 1 heat recovery apparatus 10 includes a rectangular section elongate chamber 11 having headers 12 and 13 at respective ends thereof and an outlet chamber 14 disposed between the header 13 and its associated end of the chamber 11.

The drain from the processes, or a reservoir of the contaminated water produced by the process, is connected to an inlet 15 of header 12 via a pipe line 16, in which is disposed a pump 17 having valves 1 8 and 1 9 on either side thereof. The pump 1 7 is preferably a gear pump which will break up any solid contamination in the contaminated water.

Inlet 20 of the header 1 3 is connected to a source of clean water, e.g. the mains, by means of a pipeline 21, in which is disposed a pump 22 having valves 23 and 24 on respective sides thereof. A back flush line 25 extends from the down stream end of the pump 22 to the inlet 15 of the header 12. Line 25 is also connected to an inlet 26 at the top of the chamber 11. Valves 27 and 28 are provided in the back-flush line 25 so that it can be isolated from the rest of the apparatus.

The chamber 11 and header 12 are provided with connections to a drain at their bottoms and the outlet chamber 14 has an outlet 29 disposed in its bottom.

Referring to Figures 2 and 3 the chamber 11 contains a plurality of spaced parallel rectangular section pipes 30, each extending from the header 12 along a part of the length of chamber 11 and terminating at a respective open end. The pipes 30 are arranged in an array as indicated in Figure 2. A respective twisted pipe 31 extends from the header 13 through the outlet chamber 14, into the chamber 11 and along a substantial portion of the length of its associated pipe 30 entering through the open end thereof. Each twisted pipe 31 then doubles back along its associated pipe 30 and debouches into the outlet chamber 14.

The walls of pipes 31 are deformed to create one or more flutes, each flute comprising both an internal spiral groove and a complementary spiral rib.

In use, the pumps 1 7 and 22 are switched on filling header 1 2 with contaminated water, and the header 1 3 with clean water. The contaminated water then flows along pipes 30 and out of their open free ends into chamber 11 and thence to drain. The clean water, from header 13, passes along pipes 31 into outlet chamber 14 from whence it is pumped away for use in the process or, in the case of a block of flats for heating purposes. As the hot water flows along pipes 30 it gives up its heat, by conduction, to the clean water flowing in pipes 31. Thus the clean water flowing from outlet member 14 is to a great extent pre-heated.

The arrangement of pipes 30 and 31 allows the contaminated water to be pumped past the pipes 31 at a controlled rate. This rate can be selected such that the contamination in the water silts up the pipes 30 as little as possible, whilst still providing a high level of heat transference between the flowing liquids.

From time to time the pipes 30 may become silted up in which case valves 1 9 and 24 are closed and valve 27 is opened. Clean water is then pumped into chamber 11 through inlet 26 and as the drain of chamber 11 is closed, the chamber 11 fills flushing the pipes 30 by reverse flow into the header 1 2. The flushed material then goes to the drain. At the end of this flushing process the drain of chamber 11 should be opened so as to enable chamber 11 itself to be flushed. Alternatively valve 28 may also be opened to enable pipes 30 to be forward flushed; in this case inlet 26 of chamber 11 should be closed.

The apparatus 10 therefore reduces the rate of silting by the contamination, in the water whilst facilitating the flushing of any silting which does occur.

It will be appreciated that the apparatus is particularly for use with water contaminated by solid material and that the invention also includes a method of recovering heat from such contaminated water.

It will be appreciated that chamber 11 may be cylindrical as may be pipes 30. In a simpler form the pipes 31 may merely extend lengthwise through pipes 30, without doubling back, and debouch into an outlet chamber adjacent header 12.

Claims

1. Apparatus for recovering heat from contaminated water, comprising a chamber having a drain, an inlet for contaminated water, a plurality of pipes extending across the chamber, each of the pipes having one end connected to the inlet for contaminated water and being open to the chamber at their respective other end; an inlet for clean water, a plurality of further pipes, each of the further pipes extending from the clean water inlet along a respective one of the first mentioned pipes to an outlet and means for flushing the first mentioned pipes, the arrangement being such that, in use, contaminated water flows from the inlet along the first mentioned pipes into the chamber heating the clean water flowing along the further pipes.

2. Apparatus as claimed in claim 1 further comprising a header at one or both of the inlets.

3. Apparatus as claimed in claim 2, wherein the chamber is elongate and the first mentioned pipes extend from one end of the chamber parallel to the axis of the chamber.

4. Apparatus as claimed in claim 3, wherein the further pipes extend from the other end of the chamber.

5. Apparatus as claimed in any one of the preceding claims, wherein the further pipes are doubled back within the first mentioned pipes so that they enter and exit from the first mentioned pipes at the open other end thereof.

6. Apparatus as claimed in any one of the preceding claims wherein the walls of the further tubes are deformed to create one or more flutes, each flute comprising both an internal spiral groove and a complementary spiral rib.

7. Apparatus as claimed in any one of claims 1 to 5, wherein the further pipes have ribs or fins extending lengthwise along their outer walls.

8. Apparatus as claimed in claim 7, wherein the ribs are spirals.

9. Apparatus as claimed in any one of the preceding claims wherein the first mentioned pipes are rectangular or circular in cross-section.

10. Apparatus as claimed in any one of the preceding claims wherein the means for flushing are arranged to flush the first mentioned pipes in either direction.

11. Apparatus for recovering heat from contaminated water substantially as hereinbefore described with reference to the accompanying drawings.